Stereoscopy, or three dimensional imaging, relates to any technique that records three dimensional visual information and creates an illusion of enhanced depth in a user's perceived image. Traditional two dimensional images utilize human visual cues of occlusion of one object by another, convergence of parallel edges, change in size of textured patterns, haze, desaturation, shift to bluishness, and subtended visual angle. Stereoscopy enhances the illusion of depth in motion pictures, photographs, and other two dimensional images by presenting slightly different images to each eye, and thereby adding the human visual cue of stereopsis.
Glasses for viewing three dimensional images exist in two categories: active and passive. Among active 3-D glasses are liquid crystal shutter glasses and display glasses. Liquid crystal shutter glasses contain liquid crystal that blocks or passes light through synchronization with images on a computer display, using alternate frame sequencing. Stereoscopic head-mounted displays include one display per eye, which display a different perspective near each eye, and are not used in conjunction with an external screen to be viewed at distance. Examples of active 3-D glasses include Active shutter glasses lens controlled by infrared (IR), radio frequency (RF), DLP-LINK®, BLUE-TOOTH® TRANSMITTER which use electronic component to receive signal from emitter connected to display to activate a light shutter with the frequency of 120 Hertz or 240 Hertz or more.
Passive 3-D glasses include linearly-polarized glasses, circularly-polarized glasses, infitec glasses, complementary color analyphs, chromadepth method glasses, anachrome compatible color analyph glasses, and red-eye shutter glasses where the most prevalent would be linearly-polarized glasses and circularly-polarized glasses. Linearly polarized glasses are used when a stereoscopic motion picture is projected and superimposed on the same screen through orthogonal polarizing filters. The viewer wears glasses containing orthogonal polarizing filters, which only pass through similarly polarized light and block orthogonally polarized light, allowing the viewer to only see one of the images in each eye to achieve a 3-D effect. Viewers must keep their heads level in order to prevent bleeding of images from the left and right channels into the opposite channel.
Circularly polarized glasses are used in circumstances where two images are projected superimposed onto a screen through circular polarizing filters of opposite handedness. The user wears eyeglasses which contain a pair of circular polarizing filters mounted in reverse, whereby light that is left-circularly polarized is extinguished by the right-handed analyzer and light that is right-circularly polarized is extinguished by the left-handed analyzer. This allows the user to tilt his head while viewing stereoscopic images and still maintain left and right separation.
Passive linear lenses exploit the wavelength difference between blue and red color lenses to create a 3-D effect. However, this method results in a perceived image that deviates from the actual color of the object.
Circularly polarized glasses have the advantage over linear polarized glasses because viewers with circularly polarized glasses may tilt their heads and look about without a disturbing loss of 3-D perception, whereas viewers using linear polarized glasses must keep their heads aligned within a narrow range of tilt for effective 3-D perception, or risk seeing double or darkened images.
Passive circularly polarized lenses in the market currently use flat lenses, which do not match the user's eyeball curvature and cause eye fatigue and discomfort. In addition, 3D effects is distorted if the viewers tilts their head beyond a certain angle from direct viewing of the screen. Despite the apparent short falls of the flat lens design, current market continues to utilize flat lens approach because distortion would result from curving the flat lens after molding and cutting the lens to suit the eye curvature. Specifically, this is caused primarily due to the fact that such method would rearrange the molecules in the film and degrade visual clarity.
As for active 3-D technology, the active shutter glass lens needs to be in a dark room in order to realize better resolution and full stereoscopic sensation. Some people like this but some will feel uncomfortable as well as their eyes and brain will get tired in a longer period time over than 2 hours. Moreover, although active shutter glass lens has high resolution, the flat shape of frame and heavier than usual weight cause increased eye strain, eye pressure, and induce nausea and headache when wore over long periods of time. Further, due to the flat lens shape, such lenses do not match the natural curvature of the eye. Due to the flashing of stereoscopic images at 120 Hertz or more, it tends to cause greater eye discomfort without a lens curvature. Thus, this invention also aims to create curvature lens for active 3D glasses.
Taken as a whole, current construction of flat lens, both active and passive, limits the frame shape and design. Even when we try to use flat sheet laminated to cut shape and with heating to bend; it reduces the resolution of viewing, and lead to discomfort in eyes and brain. Thus, the present invention solves the problem by continuously stretching the polarized lens and forming the lens into curved shape.
Further, a retarder is an optical device that alters the polarization state of a light wave traveling through it. The new method of processing the retarder with new laminate technology improves the 3-D stereoscopic image. The linear polarized film or partially circular polarized film is glued to the retarder inside the retarder include gap filling agent. The epoxy liquid is laminated outside the retarder then cured with air or UV light to create a “3-D circular polarized function card”. The new function card will have a better birefrigent effect without extra polymer sheets, thus improving transmission. Currently state of the art allows for 60-85% transmission. Also current market uses polymer sheets to support the linear polarizer. The use of polymer sheet requires moist glue, which interferes with transmission. This support must be assembled using half-dry glue on the lens, which negatively affects lens clarity. Dry glue cannot be used in this assembly due to the limiting nature of the thick polymer retarder and linear polarizer.
In our invention, the thinness of the retarder and PVA film (polarizer) allows the application of almost crystallized lamination possible. Specifically, the present invention solves this problem through a process by which a thin retarder and PVA or circular polarizer may be produced and assembled with dry glue. This process allows the wearer to view stereoscopic images for a longer time period without discomfort. The process entails application of organic polyvinyl alcohol (PVA) or any selection among polymer polyurethane (PU), polyvinyl chloride (PVC), polypropylene (PP), polycarbonate (PC), or polyester (PE) as the ingredient to create retarder film with linear or partially circular polarization on different surfaces, such as flat and curved sheets, as a substantial improvement to current flat 3-D lenses and to end user viewing comfort. Other advantages of these methods versus previous methods include making distortion-free, thinner, flexible, functional, comparable, durable, optimal-performance circular polarized 3D lens. This innovative method allows for conformation of the lens shape onto a flat and curved surface when the lens is still malleable and moist rather than cutting the lens from a flat sheet of polymer.